Multiple stage air-conditioning system



m 7 6 uuuu II. E 0, a Lm WM m m M 5. m R 3 E M i 2 m Q m e A. B. NEWTONI MULTIPLE STAGE AIR CONDITIONING SYSTEM July 17, 1951 Filed Aug 1'7,1945 July 17, 1951 A. B. NEWTON MULTIPLE smcs AIR commoumc svsrm 2Sheets-Sheet 2 Filed Aug. 1'7. 1945 INVENTO/i' fiLWIN d. NEWTUN HTTORNEYPatented July 17, 1951 UNITED :STATES PATENT orr cr.

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MULTIPLE STAGE AIR-CONDITIONING SYSTEM Alvin 3. Newton, Dayton, om,amour a m..-

neapolis-Honeywell Regulator Company, Minneapolis, Minn a corporation oiDelaware Application August 17, 1945, Serial No.6l1,l33

1 12 Claims.

The present invention is directed to the control of apparatus forheating and cooling enclosed spaces.

The conditioning of air for enclosures by either heating or cooling isold and well known. Howtrolling both heating and cooling equipment andwherein means are provided insuring a predetermined minimum diiferentialbetween the heating and cooling control points.

ever, the use in residencesof air conditioning apparatus incorporatingboth heating and cooling equipment is not as common as might beexpected. When both heating and cooling equipment has been provided, ithas been usual to provide a separate control system for each, withsuitable means, such as a. manually operated switch or an extrathermostat, for determining whether the heating or cooling equipmentwill be used. Not only has this sort control been costly and demandingof more attention than desirable, but it has also resulted in impropercontrol under some circumstances. For instance, if the control point forthe heating be set too close to the control point for cooling.intermittent, and in some instances, simultaneous, heating and coolingmay take place.

The present invention is directed to a relatively simple and fool-proofcontrol apparatus for air conditioning equipment'such as described. Itis therefore a principal object to provide relatively simple andeffective control apparatus for control of both heating and coolingequipment of an air conditioning system.

It is a further object to provide control apparatus which may be used,with only minor modifications, for various combinations of heating andcooling equipment such as independent heating and cooling equipment,steam or hot water heating equipment and absorption cooling means havinga common boiler, reverse cycle systems, and

vide apparatus which permits plural stage con-' trol of the conditioningequipment or which may It is an additional object to provide controlapparatus for both heating and cooling equipment wherein the operatingdifferentials on both the heating and cooling cycles may be individuallyadjusted. v

It is another object to provide control apparatus for temperaturechanging equipment including a unidirectional motor for varying flowcontrol means and for adjusting switch means and wherein said switchmeans forms part of a holding circuit for said apparatus.

It is also an object of this invention to provide automatic controlapparatus which is inherently safe and dependable and requires a minimumof manual attention.

It is a further object to provide control apparatus for temperaturechanging equipment in which a plural stage thermostat selects thetemperature changing equipment to be used with its first stage andcauses operation of said equipment with its second stage.

It is another object to provide a control device for both heating andcooling control wherein plural stage operation is provided for eitherheating or cooling and where the control points for I upon a study ofthe following specification and provide plural stage operation of onesort and single stage operation of another sort.

It is also an object to provide control apparatus for plural stagecontrol of temperature changing equipment wherein a desired sequence ofoperation of the stages is assured at all times.

It is a further object of this invention to provide control apparatuswhich includes suitable limit and safety controls and-means forregulating accessory equipment, such as fans, pumps, and the like.

It is an additional object to provide control equipment including asingle thermostat for conheating and cooling are individually adjustablesubject to a predetermined minimum diii'erential. It is an object toprovide a thermostat having a movable switch member carrying a pluralityof switch blades electrically insulated from each other.

These and other objects will become apparent drawings wherein:

Figure 1 schematically shows the present control apparatus applied to anair conditioning system having a boiler common to both the heating andthe cooling equipment.

Figure 2 schematically shows a slightly modifled control apparatusapplied to an air conditioning system using conventional heating andcooling equipment.

In Figure 1, the present air conditioning apparatus includes duct llthrough which the air being treated is circulated. A heat exchanger IIis located within duct III for heating the air, heat exchanger I2 isprovided for cooling the air, and motor driven fan l3 circulates theair. Heat exchanger il receives steam from boiler H through three-wayvalve i5 and pipe l8, condensate being returned through pipe I], checkvalve l8 and pipe l8 back to the boiler. Boiler I4 is conventional innature and is capable of giving two stages of heat, in a manner to belater described.

Heat exchanger l2 may be the evaporator of a suitable refrigeratingsystem, but for the purpose of this description, it may be considered asmerely a heat exchanger through which cooled brine is circulated, thebrine being cooled by refrigerating apparatus 28. The brine is suppliedthrough pipe 2|, returned throughpipe 22, and cooled in pipe coil 23,said pipe coil being in heat exchange relation with the evaporator ofthe refrigerating means 28. If desired, circulating means, not shown,may be provided for the brine circuit.

Refrigerating apparatus 28 is of the absorption type but obviously mayutilize the jet principle or comprise any other known type of heatactuated refrigerating means. As the refrigerating apparatus per seforms no part of the present invention, and such apparatus is wellknown, further description seems unwarranted. Refrigerator 28 issupplied steam from boiler [4 through threeway valve I5 and pipe 24 topipe coil 25 and condensate is returned through pipe 28, check valve 21,and pipe |8 to the boiler. Conduits 28 and 28 are used for circulationof a cooling fluid, such as air or water, for carrying away heat fromthe absorber and condenser of the refrigerating apparatus. A vent pipe38 may be connected by pipe to the heating coil 25 for limiting thepressure therein to atmospheric.

Temperature responsive device 3|, responding to the presence of steam insaid vent pipe 38, includes a bulb 32 disposed in said vent pipe, aconnected bellows 33, and a mercury switch 34 actuated by said bellowsin a manner to open its contacts on a temperature rise in said bulbindicating the presence of steam. Obviously, the pre cise form of thisdevice will depend on the apparatus to which it is applied and, ofcourse, it may respond to pressure instead of temperature if desired.Obviously, other safety switches or limit controls may be used withtemperature responsive means 3| or instead of the same.

Three-way valve l5 includes a movable member 36 operated by a pivotedbell crank 31 which in turn is operated by a reciprocable connecting rod38. In the position shown in Figure 1, with rod 38 in its lowermostposition and member 36 at its extreme right of travel, steam isdelivered from the boiler |4 through-pipe l6, whereas if member 36 bemoved to the extreme left of its travel by rod 38 being actuated to itsuppermost position, steam would then be delivered from the boiler topipe 24.

Connecting rod 38 is actuated by a shaft 48 having a crank portion 4|,said shaft 48 being driven through reduction gearing 42 by electricmotor 43. In addition to crank portion 4|, shaft 48 has attached theretocams 45, 46, and 41. Cam 41 includes a raised portion 48 and operates apivoted mercury switch 48 in a manner to close its contacts when saidraised portion 48 is up. Cam 46 is similar to cam 41 but has its raisedportion 58 180 degrees displaced from portion 48 of cam 41. Cam 48operates mercury switch 5| to close its contacts when portion 58 is up.

Cam has a low portion 54 of substantially 180 degrees angular extent, anintermediate portion 55, and a high portion 56, and controls thepositions of switch arms 51 and 58, having cam followers 58 and 88,respectively. Cam followers 58 and 68 are held in engagement with cam 45by a tension spring 8| extending between the switch arms. Switch arms 51and 58 are pivoted at 63 and 64 and are provided at their other endswith flexible switch blades 65 and 66, respectively. Blade 65 is adaptedto engage stationary flexible switch blade 81 when cam follower 58 is onportion 56 of cam 45 and to engage stationary contact 88 of fixed member18 when follower 58 is on cam portion 54, and lie between and in spacedrelation to blades 61 and contact 88 when follower 58 is on cam portion55. In a like manner, blade 66 is adapted to engage stationary flexibleswitch blade 88 when follower 68 is on portion 56 of cam 45, to engagestationary contact 12 of member 18 when follower88 is on cam portion 54,and to lie between and in spaced relation to blade 88 and contact 12when follower 88 is on cam portion 55. A fixed member 1| of channelshape and generally similar to member 18 extends between blades 61 and68 and includes contact portions 13 and 14 normally engaging blades 81and 68, respectively, and serving as a stop means limiting innermovement of said blades. How ever, when either switch arm 51 or 58 ismoved outwardly due to the respective follower engaging high portion 56of cam 45, then either blade 61 will be moved out of engagement withcontact 13 or blade 88 will be moved out of engagement with contact 14,respectively. Members 18 and 1|, blades 81 and 68 and switch arms 51 and58 function in electrical circuits to be described.

Primary control over motor 43 and the switches controlled thereby iseffected by a thermostat 88 responsive to the temperature of the airbeing treated. Thermostat 88 comprises a curved bimetal attached at oneend by bracket 82 to stationary post 83. A depending arm 84 is attachedto the other end of bimetal 8| and carries a flexible contact member orblade 85 at its lower end. Flexible contact blades 86 and 81 arearranged together on the left side of blade 84 and insulated therefromby electrical insulation 88, while similar blades 88 and 88 are arrangedon the right side of blade 84 and insulated therefrom by insulation 8|.Coacting with the contact blades are a series of contacts carried byadjustable arms 82 and 83, each of said adjustable arms being pivoted onor near post 83. Arm 82 has an abutment portion 84 and an indicatingportion 85 movable along scale 88, while arm 83 has an abutment portion81 and an indicating portion 88 for movement along said scale. Arm 82carries contacts |8|, I82, and I88, engageable by blades 85, 86, and 81,respectively, each of said contacts being electrically insulated fromsaid arm. Arm 83 carries contacts I85, I88, and |81 engageable by blades85. 88, and 88, respectively, each of these contacts being insulatedfrom arm 83. Preferably, each of these contacts is individuallyadjustable. Thermostat 88 also includes anticipating heater I88 andmanual switch I88. Bimetal 8| moves arm 84 to the left on temperaturefall and to the right on temperature rise, and contacts |8|, I82, and|83, or contacts I85, I86, and I81 are engaged in sequence by theirrespective coacting blades upon a sufficient change in temperature ineither direction. Engagement of abutment portions 84 and 81 is effectiveto provide a minimum differential of temperature between heatin andcooling cycles, thus preventing a slight overshoot in temperature changeby one cycle from causing operation of the other cycle. Obviously, thisdifferential may be increased if desired and either of the arms 82 or 83may be adjusted for any desired temperature within the range of theinstrument, except that 88 and 85 are prevented Burnersllltheconstruction of II2 represents that of H3.

Valve H2 is of a conventioml type and includes a movable valve memberII4 havin an armature portion which can be ath'acted by electromagnetcoil "5 when to permit flow through said valve. A member' II8, attachedto member II4, extends through bellows seal II1 to-operatc switch meansI". The switch means 7 III includes mercury switches II! and I28, the

contacts of each being closed when member III rises,andopenedwhenII5isinaioweredposltion. Valve II3is similar to 2, as before noted. andincludes a mercury switch I23 actuated by member I22 of said valve.Switch means I23 includes contact I24, common contact I25, and contactI25, with a circuit closed through contacts I24 and I25 and openedbetween contacts I25 and I25 when member I22 is lowered; due to thevalve being clomd. The circuit is opened denser and evaporator of therefrigerating apparatus, in a desired manner. Instead of using pluralstages of heating for the boiler, plural stages of compressing equipmentmay be likewise controlled. Further, the present disclosure shows twostages of operation, but this is only illustrative. Any desired numberof stages of operation can be used. As before noted, the present us ofsafety devices, limit switches, fan control means, and the like, areillustrative only and obviously may take other forms and respond todifferent conditions than those herein described. In addition, device 88may be constructed to respond to conditions other than temperature or toa combination of such factors as humidity, air,

, motion, temperature, and radiations. To more between contacts I24 andI25 and closed through contacts I25 and I28 when member I22 is raised.

Boiler I4 is equipped with the rather conventional safety devices suchas a low water cut-out I38 which includes a float operated pivoted leverI3I carrying a mercury switch I32. Mercury switch I32 has acontact I38,a common contact I34, and a contact I35 located at the opposite end ofthe switch from contact I83. A suitably connected pipe I35 suppliesmake-up water to the boiler under control of solenoid valve I31. saidsolenoid valve being controlled by said low water cut-out in a manner tobe described. Boiler I4 is also provided with a pressure actu ateddevice I48 including expansible bellows MI and mercury switch I42 andoperates in a manner to open the contacts of mercury switch I42 when thepressure in the boiler above a predetermined value.

The energization of fan I3 is controlled by a relay I45 which comprisesa winding I45, a movable switoh arm I41, and a stationary contact I48.Energization of the relay may be controlled by temperature responsivemeans I58 including a bulb I5I charged with an expansible fluid andstrapped to pipe I5 in heat exchange relation thereto. A bellows I52 isconnected to said bulb and operates a mercury switch I53 in a mannertoclose its contacts when the temperature in said bulb I5I rises to apredetermined value. Relay "5' can also be controlled by mercury switch48 or manual switch I88, as will be noted. Current for the presentcontrol apparatus is supplied by a transformer I55 having a secondarywinding I55 and a primary winding I51. Primary winding I51 is energizedfrom line wires I58 and I58.

While the present apparatus has been set forth rather specifically, itis noted that many substitutions and equivalents come to mind. Forinstance, instead of using heating and cooling equipment supplied energyfrom a common boiler, it is apparent that a reverse cycle refrigeratingappartus may be used with bell crank 31 controlling means for divertingthe flow of refrigerant through the refrigerating equipment or forcontrolling the flow of treated air and the cooling air for theequipment over the confully describe the present invention, thefollowing operation schedule will describe the function of the abovedescribed appartus.

Operation With the present equipment in the position shown in Figure 1,the apparatus is all at rest and no part of the equipment isfunctioning. None of the blades of the thermostat are in contact withtheir respectve stationary contacts, hence there is no demand for airtreatment. Arms 82 and 83 are adjusted for a minimum differential of,say 5 degrees, indicator portion 85 is adjusted for a temperature of 72degrees, and indicator portion 88 is adjusted for a temperature of 77degrees. Assuming that a 2 degree differential is to be maintained onthe heating cycle, itmay then be further assumed that blade 85 engagescontact I8I at 73 degrees, blade 88 engages contact I82 at 72 degrees,and blade ,81 engages con- IBIfbracket 82, bimetal 8|, arm 84, contactblade 85, contact I8I, wire I52, blade 88, contact 14, member 1I, wireI83, contact I34 of switch I82, contact I83, wire I84, mercury switchI42, wire I85, wire I88,mercury switch 5I, wire I81, wire I88, wire I88,blades 88 and 88, wire I18, and blades 88 and 81. This circuit, it isnoted, does not return to the secondary of the transformer hence nothingis energized, and the equipment remains inactive. However, should thetemperature continue to fall to '72 degrees, and blade 88 make contactwith I82, the previously noted circuit is completed as follows: wireI18, blade .85, contact I82, wire I12, wire I13, contact I25 of switchI23, contact I24, wire I14, wire I15, electromagnet coil 5 of valve II2,wire I18, wire. I11, wire I18, and transformer secondary I58.

A complete circuit is thus made and electromagnet coil H5 is energized,thus opening valve 2 and permitting a flow of fuel therethrough andcausing operation of burner I I I. Because member 35 of valve I5 is inits extreme right position, steam generated in boiler I4 is deliveredthrough pipe I8 to heat exchanger II and condensate formed in said heatexchanger is'returned to the boiler through pipe I1, check valve I8 andpipe I8, as before described. When the steam flow is suiiicientlyestablished as to raise the temperature of bulb I5I to, for instance,200 degrees, mercury switch I58 of device I58 is actuated to close itscontacts. Closing of the contacts of device I50 energizes motor drivenfan I3 as follows: secondary winding I56, wire I60, relay coil I46, wireI6I, wire I62, mercury switch I53, wire I63, wire I04, wire I16, andsecondary winding I56 of the transformer. Energizing of coil I46 ofrelay I45 pulls switch arm I41 into engagement with contact I46 and thefan motor is energized by the circuit: line wire I56, switch arm I41,contact I46, wire I65, fan I3, and line wire I65.

It is thus noted that a fall in temperature to '12 degrees energizes onestage of burner operation and circulating fan I3 is placed in operationwhen suflicient heat is supplied to heat exchanger II to prevent coldair from being circulated through the system. If by chance, uponenergizing of the initial circuit of the system as above described, lowwater cut-out I30 would have indicated a low water level, and arm I3Iwould have been raised to tip mercury switch I32 so that contact wouldbe made between contacts I34 and I35, solenoid valve I31 would then beenergized to permit the addition of make-up water by the followingcircuit: secondary winding I66, wire I60, wire I6I, bracket 32, bimetal6I, arm 04, blade 65, contact IOI, wire I62, blade 63, contact 14,member I I, wire I53, contact I34, contact I35, wire I90, solenoid valveI31, wire I9I, wire I92, wire I11, and wire I16 back to secondarywinding I56. Energizing of solenoid valve I31 causes it to open andpermits water to flow in through pipe I36 to furnish the water needed inthe boiler. When suiiicient water has been introduced into the boiler toraise the water level suiiiciently to again tip arm I3I down and to makeengagement between contacts I33 and I34 and to break engagement betweencontacts I34 and I35, the energizing circuit for the solenoid valve isbroken and the water flow stopped. The circuit previously set forth forenergizing the first stage of the boiler heat is then reestablished andthe boiler can be energized in the manner previously related. It isnoted that when the circuit was broken between contacts I33 and I34, dueto low water, the energizing circuit for valve II2 was likewise broken,hence there could be no boiler operation. As device I40 is also inseries in the same circuit as contacts I33 and I34, excessive pressurein the boiler will cause opening of the circuit in mercury switch I42and thereby prevent operation of the boiler. Low water cutout I30 andpressure responsive device I40 thus constitute safety devices forsafeguarding the operation of the boiler.

With one stage of heat being supplied by boiler I4, let it be assumedthat the temperature begins to rise. First, however, note that theopening of valve II2 resulted in tipping switch means II6 so that thecontacts of mercury switches H9 and I20 were closed. When thetemperature rises above '72 degrees and blade 66 separates from contactI02, valve H2 is held open by a circuit traced as follows: secondarywinding I56, wire I60, wire I6I, bracket 02, bimetal 6I, arm 04, blade65, contact IOI, wire I62, blade 66, contact 14, member 1i, wire I63,contact I34, contact I33, wire I64, switch I42,

' wire I65, wire I66, wire I61, wire I66, wire I94,

switch H9, wire I19, wire I15, electromagnet coil II5, wire I16, wireI11, and wire I16 back to transformer secondary I56. It is thus notedthat switch I I9, upon its closure, permits a holding circuit to beestablished which is controlled by blade 65 and contact IOI. Should thetemperature continue to rise to and above 73 degrees so that blade 65separates from IN, this holding circuit would be broken, electromagnetcoil II5 would be deenergized, and valve II2 would then close. Thiswould tip switch H6 so that the contacts of mercury switch II3 wouldagain be opened.

Going back to the stage of operation of the boiler wherein one burner isoperating and the temperature is still below 72 degrees, assume that thetemperature continues to drop and reaches 71 degrees. At this point,blade 61 engages contact I63 and burner H6 is brought into operation.With a completed circuit from secondary winding I56 through to wire I10due to the energizing of the first stage of operation, the second stagemay be energized by the circuit starting with wire I10 as follows: wireI10, blade 61, contact I03, wire I55, anticipating heater I06, wire I36,wire I31, switch I20, wire I96, wire I99, solenoid valve II3, wire 200,wire I92, wire I11. and wire I16 back to transformer secondary I56.Energizing solenoid valve II3 causes it to open and to permit fuel toflow to burner IIO, thus providing both stages of heat for boiler I4. Inaddition to opening valve II3, member I22 tips mercury switch I23 sothat a circuit is made through contacts I25 and I26 and is brokenbetween contacts I24 and I25.

Withthe room temperature below 71 degrees and both stages of heat beingsupplied, let it now be assumed that the temperature rises. A rise intemperature will be due to the high rate of heat output of the boilerand may take place with fair rapidity. To anticipate the rise oftemperature, it is noted that anticipating heater I06 adjacent bimetalBI is energized so long as blade 61 engages contact I03. With heater I00energized, it emits some heat and tends to open the contacts of thethermostats sooner than they would otherwise open to thus preventovershooting of the temperature due to the rapid rate of heating. Now,due to the combined effects of the rise in room temperature due to bothstages of burner operation, and due to the effects of heater I06, blade61 now breaks away from contact I03. Obviously, this deenergizes heaterI06, hence its effect on the bimetal 6I rapidly diminishes. However,both burners continue in operation due to a holding circuit for valveII3 established through blade 66 as follows: starting with wire I10,blade 66, contact I02, wire I12, wire I13, contact I25, contact I26,wire "I, wire I69, solenoid valve II3, wire 200, wire I92, wire I11,wire I18, and transformer secondary winding I56. It is thus noted thatblade 66 controls a holding circuit for the second stage of burneroperation. If the temperature should now rise above '72 degrees, andblade 66 separates from contact I02, this holding circuit would bebroken. Valve II3 would then be deenergized and closed and burner IIOwould go out because of lack of fuel. If the temperature should continueto rise to 73 degrees or higher, so that blade 65 would separate fromcontact IOI, the holding circuit for valve II2 would then open, aspreviously described, and this valve would also be deenergized, closed,and cause the stopping of burner III.

It is thus noted that means are provided for giving plural stages ofburner operation and for placing a fan in operation as soon as it wasclear that the air would be sufficiently heated to prevent harmfuldrafts. In addition, the basic energizing circuit for the valves whichcontrol 9 burner operation includes the safety devices associated withthe boiler so that burner operation can take place only when conditionsare favorable. It should also be noted that'the first stage of burneroperation, controlled by valve II2, cannot be initiated unless valve H3is closed due to the first made circuit going through contacts I25 andI24 of switch I25. In addition, it is noted that the initialenergization of valve III cannot take place until the contacts areclosed in switch I20 due to the opening of valve II2. Because of theswitch controlled interlocking means, the valves must open in theirpredetermined sequence, thus assuring-proper operation. With thetemperature now above '13 degrees, 'and no' more heat being generated,

steam flow through pipe I stops, the. temperature at bulb I5I falls,bellows I52 collapsesgand deenergizesrelay coil I45, hencearm I41"disen.

gages .-contact I45 and motor'drive'n fan I5 stops. However, if itshould be desired to operate the fan when neither heating nor coolingisprovided, this can be done by closing manual switchyllll- This energizesrelay I45. as followsrsecondary winding I55, wire I, coil- I45, wireI5I, wire 254, wire 205, switch I05, wire 255, wire I15, and secondarywinding I55.

is required. V v If the temperature in the spaceshouldnow rise to 76degrees, blade 55 would then engage contacts I05. This will initiateoperation-of motor 45 in the following manner: secondary winding I55,wire I55, wire I5], bracket 52, bimetal 5|, blade 54, blade l5, contactI45, wire 2I5, blade 51,

blade 55, armll, wire 2, wire 2I2, motor 43, wire 2I3, wire I54, andwire I15, back to secondary winding I55. Energizing motor 45 causes itto start operating. Driving through reduction gearing 42, it rotatesshaft 45 in a counterclockwise direction. The initial movement of cam45, driven by shaft 40, causes follower 5! to'fall off high portion 55of said cam in low portion 54. This breaks the initial energizingcircuit for the motor which went through blades 51 and 55. However, whenfollower 55 drops off high portion 55, blade 55 then engages contact 55of member Energizing coil' I45 places the fan in operation in themanner" pre-yg viously described. Means arethus providedfor causing thecirculation of air to'the space-being treated even though neitherheating nor cooling 3 I4 and a holding circuit for motor "is establishedas follows: secondary winding I55,: wire [55, wire 2, member 15, contact55, blade,

arm 51, wire 2, wire 2I2, motor 45, wire 215,

wire I54, and wire I back to secondary winding I55. Motor 45 thuscontinues to operate. A's cam 45 rotates, arm 55 remains in its presentposition until follower 55 rides up onhigh por-; tion 55 at which timeblade 55 then engages blade 55. However, with follower 59 still on-lowportion 54, and the holding circuitmaintained grees as have cams 45 and41. In addition, crank .portion H is now locawd with its throw in an 15wire I55, wire I55, valve H3, wire 2, wire I52,

the boiler fora higher degree of operation '01 i 10 uppermost position,connecting rod 58 is in its uppermost position, and the movable member55 of valve I5 is in its extreme left position. Valve I5 is nowpositioned to deliver steam through pipe 24 to refrigerating apparatus20.

High portion 45 of cam 41 is now uppermost and the contacts of switch 49are closed. The high portion of cam 45 is now in a lower position andthe contacts of the switch 5I are open.

If the temperature in the space should now rise to 77 degrees, and blade55 engages contact I55, the refrigerating apparatus is placed inoperation as follows: secondary winding I55, wire I50, wire I5I, bracket82, bimetal 5|, blade 54, Y blade 55, contact I05, wire. 2", blade 51,contact ll mernberjll, wire I53, contact I54, contact I33, -wire I54,switch I42, wire I55, wire 2I5, switch 54, vwire'2I5, wire, I58, wireI55, blade 59, contact the circuit through switch I55 is, opened. i'This -i.'

I55; wire 2", wire I", contact I25, contact I24,

w re. nuwire .m, electromagnet-coil H5 of ftoseodridaryQwindingIB;-Valve I12 is thus en- 'emizedandiopened1and1burner'1 I I- is placediner i a i a 3 previqusly. la q i In describing the heating cycle. Steamis "generated in boiler I4-and delivered through pipe 24, to coil-25within the heating' apparatus-zfl; and condensate from said 12in!is.ret'uri' ed pipe 25;,check valve 21,an'd pipe I5 to'the'boller"asspreviouslygdescribedgr Supplying heat to an absorption refrigerationsys'tem'causes Vat-the evaporatorofthe same in -.a mannerf-wellzknowngandl,coolsthe brine in ibe bu a. cnnnegis to circulate from coil 23through-pipe 2I,jheat exchanger I2 andpipe 22 by suitablytherefrigerating apparatus relative t'o the heat' exchanger orw jl. byproviding suitable circulating in'eans nor shown). It is noted that theinitial demand-tor" 'cooling causedclosing of the contacts of switch andcaused operation of motordriven Ian II by energizing relay I45 by'thefollowingcirc'uit: secondary winding I55, wire I5l,"relay..coil I45,

wire m, wire :04, wire 2I5, swltch m, wire I15 and secondary windingI55. The fan whfle cooling isrethus operates continuously quired.

With one stage or heat being supplied-to the I boiler for low stageoperation of refrigerating ap-.

paratus 2l, operation continues as just described; until the temperaturefalls sufliciently to'deeneri gize the apparatus, until the temperaturerises suiilciently to require second stage operation of refrigeratingapparatus. 25', or until device, JI- responds tosteam in vent 'pipe 55.

In the event of steam exhausting through vent I pipe at and raising thetemperature of bulb u -located therewithin, the higher temperature atbulb 32 expands bellows and tips mercury switch 34 to open its contacts.It wasnoted that the energizing circuit for valve I I2.went throughswitch 24, hence opening its contacts deenergizes -valve H2 and causesit to close. Device 3| thus the refrigerating apparatus. 1

Should the temperature'now rise to 78 degrees and require both stages ofoperation, blade 55 engages contact I l1 and valve 3 is energized,starting with I55 as follows: wire I55, blade 55, contact Ill, wire 22!,wire I51, switch I25,

wire I11, and wire I16 back to secondary winding I56. With both stagesof heat being supplied by boiler I4, and refrigerating equipment 20operating at its maximum output, the temperature should fall in thespace being treated. Assuming that it does fall below 18 degrees, andblade separates from contact I01, valve II3 remains energized untilblade 09 separates from contact I06, the holding circuit for the valvebeing the same as that described under the heating cycle excepting thatthe circuit is completed from wire I00 through blade 00 and wire 2I1 towire I13 instead of from wire I69 through wire I10, blade 06, contactI02 and wire I12 to wire I13.

When blade 00 separates from contact I06 and breaks the holding circuitfor I I3, the valve closes and burner IIO stops. Operation thencontinues at the low stage until blade separates from contact I05. Theholding circuit for valve H2 is the same as that described under theheating cycle excepting that the current flows from blade 04 throughblade 05, contact I05, wire 2I0, blade 01, and contact to member 1Iinstead of from blade 05 through contact IOI, wire I62, blade 60 andcontact 14 to member H, as described under the description of theheating cycle.

If, after contact 05 separates from I05, there is another demand forcooling, contact 05 will reengage contact I05 in the same manner aspreviously related. However, since the motor will have operated to aposition so that blade 65 lies between blade 61 and contact 69, andblade 61 engages contact 13, there will be no further operation of themotor and the control of the burners will function as before. However,should the next demand on the apparatus be for heating, and blade 00engage contact IIII, the re tor will be energized by the followingcircuit: transformer secondary I56, wire I60, wire I6I, bracket 02,bimetal 0I, arm 0i, blade 65, contact IOI, wire I02, blade 00, blade 66.arm 58, wire I, wire 2I2, wire 2I0, wire I04, and wire I16 back totransformer secondary I56. The initial operation of the motor willoperate cam 45 so that follower 60 will then drop off the high portion50 of the cam onto low portion 54. This will bring blade 66 into contactwith 12 and the holding circuit for motor 43 will then comprise:transformer secondary I56, wire. I60, wire 2, member 10, contact 12,blade 66, arm 50, wire 22 I, wire 2I2, motor 43, wire 2I3, wire I04, andwire I10 back to said secondary winding I56. The motor will thencontinue operating until cam 45 has rotated 180 degrees fromits previousposition and follower 60 rides upon intermediate portion 55 of cam 45 toassume the position shown in Figure 1 of the drawing. At the same time,valve member 05 will be moved from the extreme left position to theposition shown in the drawing. Then, engagement of blade 66 with contactI02 will bring on the first stage of heat in the manner previouslyrelated. Further, if the next demand should be for cooling, the motorwould again be operated upon contact being made between 05 and contactI05 as previously related.

It is noted that the present control apparatus provides plural stageoperation of means for supplying either heating or cooling for an airconditioning system without manual attention. The apparatus does notcycle between heating and cooling because the minimum differentialselected is larger than the control differential of either the heatingor the cooling cycle and the apparatus is readily adjusted to heat toany desired temperature and to cool to any desired temperature withinthe range of the equipment. In addition, both the heating and coolingequipment is operated only when safe to do so. In addition, by providingmeans for properly controlling plural stage operation of the heatingplant, no more heat is supplied for heating than is needed nor is anymore fuel burned for the cooling than is required. It is, of course,obvious that the values and the like used in the above description areillustrative only and are not to be considered in a limiting sense.

As mentioned in describing the present apparatus, many alternatives andsubstitutions come to mind. To better show the scope of the presentinvention and to give concrete form to some of the proposedalternatives, reference is made to Figure 2.

FIGURE 2 To show the flexibility of the present control apparatua'and tomake more apparent the broad scope of the present invention, the presentcontrol apparatus is,applied to an air conditioning system includingconventional heating apparatus and plural stage refrigerating equipment.Air for the space being conditioned is delivered through'duct 30I,branch duct 302 or 300, and duct 304 by suitable circulating means (notshown). A heat exchanger 306 located in branch duct 002 is supplied withheated fluid from boiler 001 through supply pipe 300 and return pipe300. Boiler 301 is of a conventional sort and er nprise. a burner 3I0controlled by a solenoid valve M I. The energization of solenoid valve 3is contro led by relay 3I3 having winding 400 and switch arms 40I- and40,0, engageable with contacts 402 and 404, respectively. Suitablesafety equipment. such as a low water cut-out in may be provided for theboiler.

A refrigerator evaporator 0I5 is located in branch duct 303 and issupplied with refrigerant from a plural stage condensing unit undercontrol of thermostatic expansion valve 0I6. Refrigerating compressors0Il, 3I0, and 020 each discharge into pipe 02I which leads to condenser222, .said condenser delivering liquid refrigerant to. thermostaticexpansion valve 3I6 through pipe 023. The vaporized refrigerant from theevaporator is returned to the compressors through pipe 324. Compressors3I0, 3I0, and 320 are driven by electric motors 325, 326, and 321,respectively.

The energization of the refrigerator compressor motors is controlled bysuitable relay means which not only controls the operation of the motorsbut also their sequence of operation. Relays 320, 320, and 330 controldirectly the operation of motors 325, 026, and 321, respectively. Inaddition, interlocking circuits including thse relays preventenergization of relay 320 unless relay 320 is deenergized; preventsenergization of relay 320 unless relay 320 is energized and 330 is notenergized, and prevents energization of relay 030 unless relay 320 isenergized.

Relay 320 includes an operating coil 430 and movable switch arms 431,442, and 440, engageable with contacts 420, I, and 449, respectively,each of said contacts being engaged when coil 433 is energized. Relay320 includes winding I and switch arms 455, 420. 461, and 45I,engageable with contacts 456, 430, 466, and 462, respectively. Contact430 is an out contact and engaged by arm 420 when relay 320 isdeenergized; the other contacts are engaged by their respective armswhen winding "I is energized.

preferred to improve flow conditions and to l3 Relay 333 includeswinding 433 and switch arms 412, 443, and 414, engageable with contacts413, 443, and 413, respectively. Contact 443 is an out" contact whereasthe other contacts are engaged when the relay 333 is energized.

- Whether air flows from duct 33l to duct 334 through duct 332 or 333 isdetermined by the operation of dampers 334 and 333 operated by levermeans 333 and 331, respectively. A central pivoted lever device 333includes a lever member 333, connected by link 343 to lever 333, and anoppositely disposed lever member 341 is con-' nected by link 342 tolever 331. A third lever member 343 of said lever device is connected byconnecting rod 344 to actuating means, to be described. Obviously, theair 'fiow through duct 332 or 333 can be adequately controlled by damper334 or 333 only, but the two dampers are lessen noise from turbulence.

An electric motor 333 operating through reduction gearing 33| drivesshaft 332 including a crank portion '333. In addition, shaft 332 hasaflixedthereon cam member 333 having a low portion 333 of substantially10rdegrees angular extent. an. intermediate portion 331, and a highportion 333. 1

Cam 333 controls the position of pivoted switch arms 333 and 33!whichgcarry switch blades 332 Y. and 333,-respectively. Arms 333and 33|also'inelude; cam followers 334 and 333, respectively.

. inactive. Assuming that indicating portion 331.

433 and 4M are separated by metallic spacer means 433.

The current for the present control apparatus is obtained from secondarywinding 4" of transformer 4| Primary winding 2 of said transformer isconnected to line wires 3 and 414.

While only a single stage of operation isshown for the heating plant, itis obvious that it could be controlled by plural stages if desired andthe refrigerating equipment could be reduced to a singlestage. These andother substitutions and alternatives are readily apparent and should bekept in mind when considering the present invention. The followingoperation schedule is intended to bring out the function of the presentapparatus and to make the present description more clear.

Operation With the apparatus in the position shown in Figure 2, it isnoted that there is no demand for temperature change and the equipmentis all of arm 333 is set at '12 degrees and portion 333 of arm 334 isset at '77 degrees, as in the description of Figure 1, then it is notedthat if the temperature drops to '73 degrees, bimetal 33! willcontact-arm 333. When the tempearture drops When cam follower 334 is onhigh portion 333 of 1 cam 333, blade 332engag'es stationary and flexibleswitch blade 333 and forces it out of engage- 'ment with contact as.Withfollower m on.

intermediate portion 331 of the cam, blade 333 is positioned betweenstationary switch blade 313 engagement with arm 432'; at '78'degre'es,arm, 432 will be forced into engagement with am 433;

and contact-31i of member 312. In normalpo sition, blade 313 engagescontact 314 or blade 333 engages contact 333. When follower 334 dropsotl! high portion 333 to low portion 333, blade 332 will thenengagecontact 313 of member 312. The movement of arms 333 and 33l and theproviding cooling. Therefore, it is convenient to start the descriptionof operation with a rising switching provided thereby will be more fullydescribed in the operation portionof this description. v

The primary control means in the present ap I paratu s is thermostat 333which is located in a suitable place so that it can respondto thetemperature of .the air being treated; Thermostat 333 comprises a strip'of bimetal 33l anchored to u the base of the thermostat at 332.Thermostat in" also includes pivoted-arms 333"and m,-

pivoted .at Y333 and 333, respectively. Blade 333 includes indicatingportion 331 and abutment portion 333, whereas arm 334 includesindicating portion-"land abutment portion 333. Indicating portions 331and 333 coact with scale 33l for adjusting the instrument, whileabutment portions 333 and 333 limitvthe minimum differential which canbe established between the heating 3 and the cooling operation of thesystem, as will be noted.

In this thermostat, however, as in that of Figure 1, the differentialmay be made wider if desiredand either arm 333 or 334 may be adjusted toany desired position, keeping in mind the minimum differentialpermitted. Arm 333 carries switch arms or blades 333, 334, and 333. Arms393 and 334 are separated by metallic separating means 333. insulatedfrom each other at its anchor portion and from the arm 333 by insulatingmeans 331. Arm 334 carries switch arms or blades 433, 43l,

433, and 434 with insulation 431 insulating the blades from each otherand from the arm. Arms Each of the blades is 7 to '72'degrees, arm 334will be forced into engagement with arm 333. ,When the temperature risesto '76 degrees, bimetal 331 will contact arm 433'.v At '77 degrees, arm4M .will be forced into a-nd'at 79 degrees, arm 433 willbe forced intoengagement with arm 434. While it was previously noted that theapparatus is inactive, it is noted that dampers 334 and 333 are adjustedto permitair flow through branch duct 333 past evapora-f tor 313. Thusthe equipment is in a position .for

temperature in the space being treated. I

- With a temperature rise, to '76 degrees, bimetal 33! engages arm 433as previously noted.- The circuit connections made are as follows:secondary winding 3, wire 423, wire 42!, bimetal 33k,- blade 433, wire422, switch blade 313, contact .314,

wire 423, wire 424, switch blade 43|, and, in

parallel with wire 424, wire 423 and contact 423 of relay 323. However,as blade 43! is connected by spacer 433 to blade 433, no circuitis'completed here. Further, contact 423 of relay 323 is not engaged. Ona further temperature rise to '17 degrees, blade 43! is forced intoengagement with blade 432 and relay 323 is energized as fol- I lows:secondary winding 4i3, wire 423, wire 42i,

bimetal 33I, blade 433, spacer 433, blade 430, blade 432,'wire 421, wire423, blade 423 and out" contact 433 of relay 323., wire 43!, wire 432,coil 433 of relay 323, wire 4 34, and wire 433 back to the otherterminal of secondary winding 3. Energizing coil 433 of relay 323 pullsin the relay and establishes a holding. circuit from wire 43lthroughwire 433. arm 431, contact 423, wire 423, wire 424, switch blade43l, spacer 433, blade 433, bimetal 33!, wire 42!, and wire 423 to thesecondary winding 3. In addition, motor 323 of compressor M3 is startedby the circuit: line wire 4, motor 323, wire 443, contact I, switch arm442, and line wire H3. The first stage of the compressing equipment isthus put into action and cooling is provided at evaporator 3|3.

Should the temperature in the space being n conditioned mu, operation ofthe motor :21!

would continue until bimetal 38i moved away from arm 488 and broke theholding circuit previously described. However, assume that thetemperature continues to rise to '78 degrees. Arm 432 is now forced intoengagement with arm 483 and relay 328 is energized to start motor 328.The circuit is as follows: secondary winding 8, wire 428, wire 42l,bimetal 3", blade 488, spacer 438, blade 4, blade 482, blade 483, wire444, blade 445, and "out" contact, 448 of relay 338, wire 441, blade 448and in" contact 448 of relay 323, wire 458, winding 45! of relay 328,wire 452, wire 453, and wire 435 back to secondary winding 8. Energizingthe relay coil 45i of relay 328 establishes a holding circuit from blade482 of thermostat 38. wire 421, wire 454, arm 455, contact 458, coil45l, wire 452, wire 453, and transformer secondary 8, this holdingcircuit remaining in operation until arm 481 moves out of engagementwith arm 482. Energizing relay 328 starts motor 328 by the circuit: linewire 3, wire 488, switch arm 4, contact 482, wire 483, motor 328, wire484, and line wire 4.

Should the temperature rise to 79 degrees, and arm 483 be forced against484 of the thermostat, the third stage of the refrigerating equipmentwill be placed in operation. The energizing circuit for relay 338 whichcontrols motor 321 is as follows: secondary winding 4i8, wire 428, wire42i, bimetal 33l, blade 488, spacer 438, blade 48l. blade 432, blade483, blade 484, wire 485, contact 488, arm 481, wire 488, coil 488, wire418, wire 453, wire 435, and secondary winding 4". Energizing coil 488of relay 338 pulls in its switch blades and establishes a holdingcircuit from thermostat blade 482, blade 483, wire 444, wire 4", arm412, contact 413, coil 488, wire 418, wire 453, and 435 to secondarywinding 4. This holding circuit is controlled by the engagement of blade483 with 482 and remains in operation until blade 482 moves out ofengagement with blade 433. In addition, motor 321 is started by thecircuit: line wire 4l3, wire 413, arm 414, contact 415, wire 418, motor321, wire 411, and line wire 4.

With all three of the compressors operating, the temperature shouldbegin to fall and the compressors will be cut out of action in reversesequence to which they were energized. In chocking the energizingcircuits for relays 328, 328, and 338, it will be noted that if all ofthe compressors are in operation and something should happen which wouldcause, for instance, relay 323 to be deenergized and stop motor 325,relay winding 433 of relay 328 cannot be reenergized because the holdingcircuit controlled by arm 431 and contact 438 is broken, and the initialenergizing circuit from wire 428 through arm 428 and contact 430 isbroken due to relay 828 being energized. Likewise, with relay 328deenergized, it cannot be reenergized unless 328 is energized and relay338 is deenergized, and relay 338 cannot be reenerg.zed unless relay 328is energized, as previously recited. Thus, by the present interlockingcircuits, relays 328, 328, and 338, and the compressors which theycontrol must always be started and operated in their proper sequence.

While no protective equipment is shown for the refrigerating equipmcnt,it is of course obvious that such may be used. Apparatus commonly usedcomprises means responsive to unduly high head pressure and means forresponding to suction pressure for preventing very low suction pressure.Apparatus of this sort, and others, may be easily connected into thepresent control apparatus by connecting same in series in wire 435.Thus, the occurrence of unduly high head pressures would stop all of thecompressors, as would very low suction pressure. of course, if it bedesired to provide protective equipment or the like in controllingrelation to any one of the compressors, this can easily be done byconnecting same in series with the relay winding for that individualcompressor.

Should the temperature in the space being conditioned now drop to 73degrees due to seasonal change or the like, and bimetal 3" move intoengagement with arm 383, motor 358 is energized as follows: transformersecondary winding 8, wire 428, wire I, bimetal 33!, blade 383. wire 438,switch blade 383, switch blade 382', arm 388, wire 4", wire 432, motor358, wire 483, and secondary winding 4l8. Motor 358, operating throughreduction gearing 35i, rotates cam 355 in a counterclockwise direction.The initial movement of cam 355 causes follower 384 to drop off highportion 353 on to low portion 358. This permits blade 382 to engagecontact 313 of member 312 and establish a holding circuit from secondarywinding 4i8 through wire 428, wire 434, wire 435, member 312, contact313, blade 382, arm 388, wire 43!, wire 432, motor 358, and wire 433back to secondary winding "8. Motor 358 will then continue to operateuntil cam follower 384 is forced upwardly by the intermediate portion351 of cam 355. This will raise contact 382 off contact 313 and breakthe holding circuit. In the new position, blade 382 will be between andspaced from contact 313 and switch blade 383; Blade 383 will then engagecontact 388. Also, cam follower 385 will be on high portion 358, andtherefore blade 383 will be in engagement with switch blade 313 andengagement will be broken between blade 318 and contact 314. Inaddition, since shaft 352 has rotated degrees, connecting rod 344 israised and rotates lever device 333 in a counterclockwise direction in amanner to move dampers 334 and 335 to a position stopping air flowthrough branch 383 and permitting air flow through duct branch 382. Theapparatus is now in a position for supplying heat to the space beingconditioned. If the temperature should now fall to '12 degrees and blade334 be forced into engagement with blade 385, boiler 381 is started inoperation by the following circuit: secondary winding 8, wire 428, wire42!, bimetal 38l, blade 383, spacer 388, blade 384, blade 385, wire 481,winding 433 of relay 3l3, wire 488, and wire 48!! back to secondarywinding 4l8. Energizing the winding 433 of relay 3" pulls blade 48l intoengagement with contact 482 to form a holding circuit, to be latertraced. Also, blade 483 is pulled into engagement with contact 484 toopen solenoid valve 3 by the following circuit: transformer secondarywinding 8, wire 428, wire 434, wire 485, blade 483, contact 484, wire488, safety control 3l2, wire 481, solenoid valve 3, wire 488, wire 488and secondary winding 8. Energizing solenoid valve 3 causes it to openand permit fuel to flow to burner 3l8 thus placing boiler 381 inoperation and providing heat for heat exchanger 388.

With boiler 381 in operation and heat being supplied to heat exchanger388, the temperature in the space being conditioned may be considered torise. When it rises above 72 degrees, and blade 384 moves out ofengagement with 385, boiler 381 is continued in operation by a holdingcircuit traced as follows: secondary equipment.

489, and wire 490 back to secondary winding 4| 0. However, both of theseholding circuits depend on bimetal 381 engaging blade 393 and when thetemperature rises to 73 degrees, and bimetal 38i leaves blade 393, theholding circuits are broken, winding 488 is deenergized,

blade 493 breaks its engagement with contact 494, solenoid valve 3closes and the boiler is shut down.

In this description, as in the description of the apparatus of Figure 1,it has been shown how both heating and cooling equipment can becontrolled from the same thermostat in a manner to provide apredetermined differential for the operation of each stage of heating orcooling and to provide automatic changeover from heating to cooling withsimple and readily available While the present control apparatus isshown in its application to two of the most common examples of heatingand cooling equipment, it is, as before noted, obvious upon inspectionthat the present control equipment is equally useful with other types ofheating and cooling equipment, such as the reverse cycle systems and thelike. Because of the wide range of equivalents and substitutions thatmay be made in the present disclosure, it is considered that the scopeof the present invention is to be limited only by the appended claims.

I claim as my inventionzi 1. In an air conditioning system including acondition changing means capable of plural stage operation, means forplacing said changing means in operative or inoperative relation to saidsystem, motor means for actuating said placing means, first switch meansoperated by said motor means, second switch means, said second switchmeans having a plurality of sequentially operable sets of contacts,condition responsive means for operating said second switch means, andcircuit means connecting said motor means, said first switch means andsaid second switch means so that operation of the first set of contactsof said second switch means causes said motor means to position saidplacing means in a desired manner and operation of the second set ofcontacts of said second switch means energizes a circuit including saidfirst switch means for causing operation of said changing means.

2. In air conditioning apparatus, temperature changing means includingheating means and cooling means, flow diverting means for selectivelyplacing either said heating means or said cooling means in operativerelation to said apparatus, motor means for operating said divertingmeans, switch means operated by said motor means, said switch meansincluding two sets of contacts, condition responsive means, secondswitch means operated by said condition responsive means, and circuitmeans connecting said heating means, said cooling means, said motormeans, the first named switch means and said second switch means in suchmanner that said second switch means and one set of contacts of thefirst named switch means controls the operation or said motor means andsaid second switch means in cooperation with the other set of contactsof the first named switch means controls the operation of the selectedone of said temperature changing means.

3. In control apparatus for fiow controlling means for air conditioningapparatus, in combination, motor means for actuating said flowcontrolling means, first switch means, second switch means, and cammeans operated by said motor means for actuating said first and secondswitch means, said cam means having a high,v

an intermediate and a low portion, said low portion extendingsubstantially half the angular extent of said cam means, one of saidswitch means controlling the energization of saidmotor means in suchmanner that said motor means is normally stopped with both of saidswitch means being positioned by the high and intermediate portions ofthe cam means.

4. In an air conditioning system-having tem- I perature changing meansincluding heating and cooling means and motor actuated means for placingeither the heating or cooling means in operative relation in the system,means for controlling said system comprising, in combination, firstswitch means operated by said motor, second switch means operated bysaid motor, temperature responsive means, third switch means operated bysaid temperature responsive means on temperature fall, fourth switchmeans operated by said temperature responsive means on temperature rise,said third and fourth switch means each including a plurality of sets ofsequentially operable contacts, and circuit means connecting saidheating and cooling means, said motor means and said switch means sothat the first set of contacts operated by said temperature responsivemeans, upon temperature change in either direction controls theoperation of said motor means and initiates a holding circuit for one ofsaid temperature changing means and the second set of contacts operatedin sequence by said temperature responsive means causes energization ofsaid temperature changing means and the completion of said holdingcircuit.

5; In an air conditioning system having plural stage temperaturechanging means and motor actuated means for placing said temperaturechanging means into or out of operative relation in said system, controlmeans for each stage of the temperature changing means, each of saidcontrol means including switch means actuated thereby,

temperature responsive means, switch means including a plurality ofsequentially operated contacts operated by said temperature responsivemeans, and circuit means connecting said motor, said control means andthe switch means actuated by said temperature responsive means in suchmanner that said control means are actuated in the same sequence as thesequentially operated switch means, the switch means operated by thecontrol means permitting the said sequence and positively preventing anyother sequence of operation.

6. In an air conditioning system having two types of treating means andmeans for placing one or the other of said treating means inoperativerelation in said system, said treating means including safetyswitch means, motor means for operating said placing means, first switchmeans operated by said motor means, second switch means, meansresponsive to a condition indicative of a need for operation of thesystem for operating said second switch means, and circuit meansconnecting said motor means, said first switch means, said safety switchmeans and said second switch means, said second switch means causingenergization of one of said treat ing means and causing said motor toposition said first switch means in a manner to permit subsequentoperation of said motor means only upon a demand for operation of saidother treating means.

7. In an air conditioning apparatus, in combination, air treating means,electrical regulating means for said treating means, safety means forsaid treating means, condition responsive means, switch means operatedby said condition responsive means, said switch means comprising firstand second sets of contacts, said sets of contacts being sequentiallyoperable, and an electrical circuit for controlling said regulatingmeans comprising in series said first set of contacts. said safetymeans, said second set of contacts and said regulating means.

8. In a cooling system, a plurality of compres sors, a relay means foreach compressor for controlling the operation of said compressor, eachof said relay means including a winding and a plurality of sets ofcontacts, plural stage condition responsive control means, and meanselectrically connecting said relays and said condition responsive meansso that the winding of at lease one relay can be energized only throughsaid condition responsive control means and a set of contacts of anotherrelay.

9. In an air conditioning system, heating means, cooling means, commonboiler means for said heating means and said cooling means, meansregulating the operation of said boiler means, diverting valve means fordirecting heated fluid to either the heating means or said coolingmeans, limit control means for said cooling means, limit control meansfor said boiler means, motor means for operating said valve means,switch means operated by said motor means, temperature responsive meansfor controlling said regulating means and said motor means, and meanselectrically connecting said regulating means, said boiler limit controlmeans, said switch means, said limit control means for said coolingmeans and said temperature responsive means so that said boiler limitcontrol means is effective for both heating and cooling operation andsaid limit control means for said cooling means is made effective bysaid switch means only when cooling is required.

10, In control apparatus for an air conditioning system having flowcontrol means, in combination, motor mean for actuating said flowcontrol means, cam means operated by said motor means, said cam meansincluding low, intermediate, and high cam surfaces, follower means forengaging said surfaces, and first, second and third switch meansoperated by said follower means in such manner that said first, second,and third switch means are operated in one manner when saidfollowenmeans engages the high surface of said cam, the first and secondswitch means are operated in a reverse manner when said follower engagesthe intermediate surface of said cam, and said third switch means isoperated in a reverse manner when said follower means engages the lowsurface of said cam.

11. In control apparatus for an air conditioning system having flowcontrol means, in combination, electric motor means'for actuating saidflow control means, cam means operated by said motor means, said cammeans including low, intermediate, and high surface portions, a pair ofoppositely disposed follower means for engaging said surfaces, andfirst, second, and third switch means operated by each of said followermeans. each of said first and third switch means being connected incurrent controlling relation to said motor means, each of said first,second, and third switch means being operated in one manner when therespective follower means engages the high cam surface portion, saidfirst and second switch means being operated in a reverse manner whensaid follower means engages the intermediate cam surface portion, andsaid third switch means is operated in a reverse manner when saidfoilower means'engages said low surface portion.

12. In control apparatus for an air conditioning system, in combination,motor means, cam means operated by said motor means, said cam meanshaving low, intermediate, and high cam surfaces, cam follower meansengaging said cam surfaces, and first and second switch means operatedby said follower means in such manner that said first and second switchmeans are onerated to open one switch means and close the other whensaid follower is on the high surface of said cam and to operate both ofsaid-switch means in a reverse manner when said follower is on theintermediate surface of said cam.

ALWIN B. NEWTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,902,979 Whiteley Mar. 28, 19332,011,787 Whiteley Aug. 20, 1935 2,291,769 Smellie Aug. 4, 19422,352,930 Anderson July 4, 1944 2,364,459 McGrath Dec. 5, 1944 2,381,427Andersson Aug. 7, 1945 2,403,798 Holmes July 9, 1946 Certificate ofCorrection Patent No. 2,561,067 July 17, 1951 ALWIN B. NEWTON It ishereby certified that error appears in the printed specification of theabove numbered patent requirlng correction as follows:

Column 6, line 26, for respectve read respeeti/ve; line 7 3, forestabilshed read established; column 7, line 28, for wire 153 read wire163; column 14, line 27, for tempearture read temperature; column 19,line 31, for lease read least;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 1st day of January, A. D. 1952.

THOMAS F. MURPHY,

Assistant Gammz'esz'oner of Patents.

Patent No. 2,561,067 July 17, 1951 ALWIN B. NEWTON It is herebycertified that error appears in the printed specification of the abovenumbered patent requiring correction as follows:

Qohmm 6, \me 26, ior respecti e read respective; line 73, foresta-bilshed read established; column 7, line 28, for wire 153 readwe're 163 column 14, line 27, for tempearture read temperature; column19, line 31, for lease read least;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 1st day of January, A. D. 1952.

[Int] THOMAS F. MURPHY,

Assistant Oommz'saz'oner of Patents.

